dt-bindings: mfd: Add Renesas R2A11302FT PMIC

dt-bindings: mfd: Add Renesas R2A11302FT PMIC

This PMIC is referenced in upstream DTs for the Renesas Lager and
Koelsch boards. Sadly, there is no documentation available. This minimal
binding description states the facts that we do know.

Fixes:
arch/arm/boot/dts/renesas/r8a7790-lager.dtb: /soc/spi@e6e10000/pmic@0: failed to match any schema with compatible: ['renesas,r2a11302ft']
arch/arm/boot/dts/renesas/r8a7791-koelsch.dtb: /soc/spi@e6e20000/pmic@0: failed to match any schema with compatible: ['renesas,r2a11302ft']

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://patch.msgid.link/20251010094734.10487-2-wsa+renesas@sang-engineering.com
Signed-off-by: Lee Jones <lee@kernel.org>